3 papers
quant-ph2026
Resource-efficient energy-based operator selection in fermionic ADAPT-VQE via exact Hamiltonian transformation
Emanuele Rossi, Erik Rosendahl Kjellgren, Artur F. Izmaylov +3
The energy-based approach to operator selection in ADAPT-VQE relies on reconstructing the one-parameter energy landscape for each operator in the pool. In fermionic implementations…
quant-ph2026
Orbital-optimized spin-adapted multistate contracted VQE for excited states and properties on quantum hardware
Erik Rosendahl Kjellgren, Karl Michael Ziems, Peter Reinholdt +3
We introduce the orbital-optimized multistate contracted variational quantum eigensolver (oo-MC-VQE) method with spin-adapted operators for the computation of ground and excited st…
quant-ph2026
Tackling instabilities of quantum Krylov subspace methods: an analysis of the numerical and statistical errors
Maria Gabriela Jordão Oliveira, Karl Michael Ziems, Nina Glaser
Krylov subspace methods are among the most extensively studied early fault-tolerant quantum algorithms for estimating ground-state energies of quantum systems. However, the rapid o…